Is Omicron worse than Delta?


Scientists need more time before they draw conclusions

The Omicron variant has dominated headlines ever since the World Health Organization designated it a COVID-19 variant of concern Nov. 26.

With that, it’s only natural to wonder how Omicron compares to the Delta variant, which has been the main variant in the U.S. — and many parts of the world — for months now. In the U.S., Delta currently is responsible for 99.9 percent of COVID-19 cases, per data from the Centers for Disease Control and Prevention (CDC). However, experts say that Omicron has a few key mutations that could potentially make it able to out-compete Delta.

With a virus as contagious as the coronavirus that causes COVID-19, any new variants that are even more transmissible than the original can cloud the path to recovery from a global pandemic. In July, the Delta variant, which scientists believe is twice as contagious as earlier ones, became the dominant variant in the U.S. and quickly resulted in a spike of COVID-19 cases and hospitalizations. The vast majority of hospitalizations and deaths have been in people who were unvaccinated.

At least 17 U.S. states and counting have reported cases of Omicron, or about a third of the country.

Right now, scientists think that Omicron is likely to be at least as contagious as Delta and that the level of contagiousness will strain health care systems if left unchecked. But they’re also confident vaccines will continue to be protective against severe disease.

According to Dec. 5 data from the CDC, 75.5 percent of Americans ages five and older have received at least one COVID-19 shot.

On Dec. 3, CDC Director Dr. Rochelle Walensky told television’s Good Morning America there were about 90,000 new cases of COVID-19 in the U.S. every day, and “about 99.9 percent of them continue to be Delta.”

As scientists work to uncover Omicron, here’s how the two variants compare right now:

  • Both Omicron and Delta are variants of the original SARS-CoV-2, the virus that causes COVID-19. “Every time this virus enters a new person, it multiples millions of times. That gives it the opportunity to mutate,” explains William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “When that happens, occasionally you get a variant.”
  • Most variants are dead-end mutations, meaning they don’t end up doing much, Dr. Schaffner says. “But every once in a while you get a mutation or a whole series of mutations that change the character of the virus,” he said. “It’s like discovering you have a new cousin. You can see it’s related to your family but it has its own personality and characteristics.”
  • The Delta variant is more than twice as contagious as previous COVID-19 variants, according to the CDC, and it may cause more severe illness than previous variants in unvaccinated people.
  • The Omicron variant has a “large number of mutations,” per the WHO, and it seems to be more likely to reinfect people who have previously had COVID-19. “Many of those mutations involve the actual spike protein, which is the critical part of the virus that allows it to enter the cells of our body and make us sick,” Dr. Schaffner said. What’s unclear right now, though, is whether Omicron is as contagious as Delta or even more infectious than Delta.

“The short answer is, we don’t know,” says Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York. However, he points out, Omicron has a large number of mutations on its spike protein which, again, is what SARS-CoV-2 uses to infect your cells. “The reason people are nervous is because of those mutations,” he said. “But are the mutations setting things up to go in a bad direction or will they cancel each other out? We just don’t know yet.”

It’s too early to tell for sure, but early signals of the severity of Omicron are “encouraging,” Dr. Anthony Fauci, President Biden’s chief medical adviser, told CNN – that is, there aren’t safety signals right now that show Omicron leads to more severe COVID-19.

Symptoms of Delta vs. Omicron

In general, symptoms of COVID-19 have remained fairly steady, regardless of variants like Omicron. Per the CDC, those include:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

Data on Omicron is still very preliminary, but one doctor who has treated Omicron patients told the BBC that people have experienced “extremely mild symptoms” with the variant so far. She also noted that the symptoms have been a little different from other strains of COVID-19.



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